Electromechanical telephone system



W. T. POWELL.

ELE'CTROMECHANICALTELEPHONE SYSTEM.

APPLICATION- FILED JAN-11.1919.

4:37, 356 o Patented Nov. 28, 1922.

INVENTOR ATTORNEY to the set of terminals in the connector switchconductors also connected as has been said,

- latter case there will be no response by the called-for party and nooperation of the connector switch circuits of apparatus under the calledsubscribers substation control. ,However, the called line individualswitch will not be caused to move tocause its wipers to make connectionwith the terminals of the outgoing or terminating trunk circuit leading"from the connector switch bank, and connection will only be made to asource of busy tone current, common to a plurality of line circuits, sothat there. will be pro- 3 ected back through the circuits of the calledline switch and through the circuits ofthe connector switch, as CN, andthrough the circuitsof the calling line switch L, back to the callingsubscriber, the busy tone apprising the subscriber that the called-forline isbusy. I

If the present invention is used in asystem having only 100 lines, therewill be 100 v line switches, such as L and M, one of which connectors,and other 10 contacts serve as is individual to each line. Each lineswitch is provided with 20 sets or" fixedcontacts, 10 of which serve asterminals for trunks leading to directly operated switches, such asterminals for incoming trunks which are employed when a line is called.Since 1t has been assumed that 10 per cent trunking is employed, there.will be 10 connector switches, each one of which has access to 100terminals corresponding to the lines of the system. In the presentarrangement the socalled talking contacts and test contacts are t notmultipled between the several connector switches, only the so-calledstarting conductor, such as-63, being multipled between the 10 connectorswitches. Two of these multiple d connections from the startingconductor 63, are shown near the bottom of the drawing' It will beunderstood that the number of lines of the system as well as the numberof the incoming and outgoing trunks and connector switches may be variedaccording to the sine and demands of the system, and that the mentionednumbers are merely used for purposes of description. 7

In order to facilitate a better understanding ofmy invention and theobjects thereof, a description will now be had of the operation of thesame made under the assumption, that it is the subscriber at thesubstation A that desires to make a call, and that a connection isdesired with the subscriber at the substation B located upon a linehaving the line switch M, and the line number of which line is assumedto be #20.

The subscriber at substation A, upon removing his receiver r, closes anenergizing circuit for the line relay LR of the line switch L asfollows: ground at G, contact 1 of the cut-off relay CO, line conductorT, contact 2 of the substation hook switch, transmitter TR, receiver 7'calling device CD, line conductor R, contact 3 of the 'cut- 01f relayCO, winding of the line relay LE to the source of current.

The line relay LR operates and closes the following circuit: ground G,contact 1 of cut-off relay CO, contact 4 of line relay LR, windingofstepping magnet ST, contact 5 of said stepping magnet, resistance coilRE to the source of current. Assuming the trunk upon which the wipers 6,7, 8, 9 and 1.0 of line switch L are resting, to be busy, this abovetraced circuit will cause the stepping magnet ST to energize, break itsown circuit at contact 5 and to then retract its armature. This causesthe wipers 6, 7, 8, 9 and 10 to be stepped tothe second'row of terminalswhere nothing is found to cause the stepping magnet ST to remaindeener-- gized, therefore it will continue to step the wipers forwarduntil the fifth row of terminals is reached which are assumed to be theterminals of the first idle trunk tested by the line switch, L. Here theswitch will be stopped because groundG'A will place a shunt around thestepping magnet winding 14, through the resistance of the winding 22 ofthe cut-otfrelay, CO which is low enough to prevent the stepping magnetST from again operating. This circuit is traced as follows: ground GA ofconnector CN, contact 16 of relay IMP, contact 18 of relay BL, normallyclosed shaft contact 19, test trunk 20, which is multipled to acorrespond ing contact of'all line switch banks of the group, terminal15, wiper 6, contact 12 of relay LR, low resistance 22 of relay CO,contactZe of relay CO, to one side of the stepping magnet winding 14.The other side of the stepping magnet winding 14 has ground G on it asbefore traced. The stepping magnet winding 14 does not get sufficientcurrent to energize its I armature, therefore the wipers 6, 7, S, 9 and10 of line switch L remain on the trunk leading to connector CN. Thissame ground, GA, which was traced to the coil winding 14; also goesthrough contact 5 of stepping magnet ST, resistance coil REto the sourceof current. This circuit, which includes winding 22 of relay CO, causesthe cut-off relay CO to operate and disconnect the line switch batterybridge from the calling line at contacts 1 and i The line conductor T isextended by way .winding of relay RL- to battery.

of contact 27 of relay CO, wiper10, terminal 28, trunk wire 29 andwinding of 1mpedance @011 B to ground GB at connector CN. Line conductorR is extended by way of contact 30 of relay CO, Wiper 9, terminal 31',trunk-wire 32 and winding of impulse relay IMP to the source of current.The closed circuit of the substation A in addition to the above tracedcircuit causes the energization of relay IMP, which in turn operatesrelay RL over the following circuit: ground GA, contact 17 of relay IMPand The instant that relay IMP operates, this particular connector CN ismade "busy to other call ing line switches like L because ground istaken off the test trunk 20 by the opening of contact 16. Ground willnot again be placed on trunk 20 until disconnection is made. is kept offof trunkEZIO during the iinpulsing of relay IMP because of the fact thatrelay RL, which is slow releasing, holds its armature attracted, andmaintains contact 18 opened while relay IMP vibrates its contacts. Upondisconnection this ground GA is not placed on trunk-20, to. cause thistrunk to test idle, until the shaft of connector CN reachesnormal andcloses oii normal contact 19.

When the relay C of line switch L operates, as previously described, itopens its own low winding 22 at contact 24 and closes its own highresistance winding 23 which looks itself over the following circuitground GC, contact 33 of connector release magnet REL, holding trunk 34,terminal 35 and wiper 8 of line'switch L, high winding 23 0f relay CO,contact 21 of relay CO, contact of stepping magnet ST, resistance RE tothe source of current. Theoperation of relay CO also disconnects thestepping magnet circuit ST from the trunk 36 of connector UN at contact26 and places the common busy tone wire 37 on the trunk 36, throughcontact and condenser 38, for a purpose to be later described. Theoperation of the relay CU also allows line relay LE- to retract'itsarmatures by openingits circuit at contact 3. 7

Assume the number desired by the calling subscriber at substationA to be20 and that number 20 is the substation shown at I3. The callingsubscriber now operates his calling device for the first digit 2 of thecalled number, whereby the substation impulse springs (not shown butwell understood) areoperated twice momentarily, each timebi'ea'lring'tlie circuit of the connector impulse relay IMP. The relayR-L of the connector being slow releasing does not deenergize during themomentary interruptions of its cirguit by the impulse relay IMP, andconsequently each time the latter deenergizes, an impulse is transmittedthrough the primary magnet PM. This circuit extends from ground GA,contact 16 of relay IMP,

contact 39 of relay EL, winding of changecircuit for operating themagnet ESQ ex tends from ground GD, contact of relay CH, winding ofmagnet ESQ, resistance coil 46 to the source of current. After the lastimpulse is delivered, the relay CPI-releases and opens the circuit formagnet ESQ, which, upon deenergizing, permits the side switch wipers40,47 and 48 to advance from first to second position. The movement ofthe side switch wiper 40 tronriirst to second position transfers theimpulse circuit from the primary magnet PM to the secondary magnet SM. i

The calling subscriber now operates his calling device for the lastdigit 0, in response to which the connector impulse relay IMP operatesto transmit ten impulses through the secondary magnet SM in series withthe relay CPL-whereby the shaft wipers 41, 42, 43 and 44 are rotatedonto the contacts of the desired line. The said circuit extends 'fromground GA, contact 16 of relay IMP, contact 39 of relay EL, winding ofrelay C'l-l, side switch wiper 40 and second position thereof, windingoi seeondary magnet SM to the source of current. The relay CH operatesin response to the impulses for this digit in the same manner as for theprevious digit to cause the escape magnet ESQ to advance the side switchwipers 40, 47 and 48 one more position, i. e., from second to thirdposition.

By the engagement of the side switch wiper 48 with its thirdpositioncontact point, a connection is completed for energizing theescape magnet as follows :ground GD, side switch wiper 48, and thirdposition contact thereof, winding of magnet- ESC, resistance coil 46 tothe source of current. This energizes the escape magnet but does notallow the side switch wipers to move away from the third position asthey are advanced upon the release of the escape magnet. Side switchwiper 47 completes a circuit to cause the called line switch M to steparound to a point on its bank corresponding to the connector CN whichconnected with it. i. e., the line switch M at this time will advance tothe sixth row of contacts on its bank (of those shown) I wipers 49 andat which point called line switch wipers 49, 50, 51, 52 and 58 will reston terminals 54, 55, 56, 57 and 58 respectively. As the connector wipers41, 42, 43 and 44 are now resting on contacts 59, 60, 61 and 62respectively, it will be seen that connection may now be establishedbetween calling substation A and called substation B. The circuit forcausing line switch M to advance to the point associated with connectorCN, as above described, is as follows: ground GE, low resistanceimpedance coil X, side switch 47 and third position thereof, connectorwiper 44, terminal 62, trunk wire 63, contact 64 of relay 0C of calledline switch M, winding 65 of stepping magnet TS, contact 66 of magnetTS, resistance coil PS to the source of current. This circuit causes themagnet TS to advance in the same man nor as described for the callingline switch L, .until the wipers reach the sixth row of terminals whenthey will be stopped by the following circuit :-ground GE, lowresistance impedance coil X, contact 67 of relayTT, contact 68 of relayCL connector wiper 41, terminal 59, trunk wire 69, terminal 57 and wiper52 of called line switch M, contact 70 of relay LE, low resistancewinding 71 and contact 72 of relay 0G to one side of stepping magnet TS.The other side of TS also goes to ground GE as previously traced,therefore, as the stepping magnet TS is shunted by the low resistancewinding 71 of relay ()0, it will not again operate. This above traced,circuit which went through winding 71 of relay QC, in addition tocausing line switch M to stop on the sixth row of terminals, causesrelay 0G to operate. Relay 06 looks over the following circuit :-groundPE, winding of impedance coil K, side switch wiper 47 and third positionthereof, winding of relay TT, connector wiper 43, terminal 61, trunkwire 73. terminal 56 and wiper 51 of line switch M, high resistancewinding 74 of relay 06, contact 75 of relay OC, contact- 66 of magnetST, resistance coil RS to the source of current. This circuit causesrelay TT to operate whose functionwill be later described.

Relay CO, in operating, removes the line switch M battery bridge fromthe called line by opening contacts '76 and 77. Relay 00 also extendsthe called line conductors V and W to the line wipers 41 and 42 of theconnector CN by way of 50 of called line switch M. Relay QC also extendsthe common battery busy tone wire 3'7 by way ot'pondenser 78, contact 79of relay 0G, trunk wire 63, con nector terminal 62, connector wiper 44to side switch 47. The tone will not be heard by the calling party atthis time because it is held disconnected from the calling line bycontact 67 of relay TT.

called line switch M, line switch wiper 50, I

contact 82 of relay 06, called line conductor.

W, condenser is, ringer W1, hook switch contact S4, conductor V, contact83 of relay OC, line switch wiper 49, terminal 54, trunk wire G9,terminal 59, connector wiper 41, contact 68 of relay CI, contact 85 ofrelay TT, re-

sistance coil 86, ground, ground GH, through the battery, commonresistance COll 87 to the other side of the generator GN. Because of thelow resistance coil 86 included in the re turn path for this signalingcurrent, part of it will be forced through condenser 92, trunk wire 29,terminal 28, line switch wiper 10, contact 27 of relay CO, lineconductor T, substation apparatus A, line conductor R, contact 30 ofrelay CO, line switch wiper 9, ter minal 31, trunk wire 32, winding ofrelay IMP, through the source of current to ground GL. This causes anaudible signal to be given the calling subscriber, notifying him thatthe called partys line is being rung. Upon the response of the calledsubscriber at substation B, relay TP, which is included in the abovetraced signaling circuit, operates because of the closed path for directcu1- rent which is formed by closing contact 88 at the hook switch.Relay TP, upon energiz ing, releases the escape magnet ESC, allowingside switch wipers 40, 47 and 48 to advance to the fourth position. Thiscircuit is traced as follows :ground GG, contact 89 of relay TP to theside of the escape magnet ESQ which goes to the source of currentthrough resistance coil 46. This short circuits magnet ESC and causes itto release.

Relay CI now energizes over the following circuit :ground GD, sideswitch wiper 48 and fourth position thereof, winding of relay CI to thesource of current. In passing it may be said that this above circuit isalso closed when side switch wiper 48 is in the second position therebyenergizing relay 01. This is for the purpose of preventing ground,through low resistance impedance coil X, being extended by way ofcontact 67 of relay TT, contact 68 of relay G1 (which would otherwise bedeenergized), connector wiper 41, a terminal like 59 being contactedwith as wiper 41 advances over it, trunk wire 69, line switch terminal57, wiper of some line switch like M resting unused at this point,contact 70 of relay LE, low resistance winding 71 of relay ()0, contact72 of relay 0C, contact 66 of magnet TS, resistance coil RS to thesource of current. If this could happen a relay DC of line switch Mwould be energized unnecessarily as a connector passes over a contactupon which the line switch was standing. By operating relay G1, whichdisconnects the low resistance path to ground this condition 'isavoided. The ground GF' through winding .90 of .coilfi'B is connected inthis circuit but because of the hlgh resistance winding 90 of coil A'Bbeing in series with the very low res stance winding 2'1 of (relay QG,the latter will not operate.

The called subscrifber now gets talking current as follows; ground GFwindmg 90 of talking bridge coil'AB, connector wiper ll, terminal 59,trunk wire 69, l nesw1tc'h' termina]. 54;, line switch w per 49, contact83 of rei lay QC, conductor VQsub tatiOn 'B, conductor VlQcontact 820irelay 06, line switch ,wipcr 50, terminal 55, trunk wire .81 termiualGOiconnector wiper 42 contact '92 of relay (ll, winding 91 of coil A13 tothe source or currentf: The calling subscriber gets talking,

currentthrougih relayIMP and battery feed coil "B the circuit or whichwas previously traced, The voice currents pass between the two throughcondensers 92 and 93.

I a "If the called "line switchM is busy when", the connector CN landson the terminals associated with it, the connector sideswitch willadvance to the third positionin the same manner as when calling anv idleline switch.v

' If the called lineswitch is busy either because of anoriginating orterminating call, its cut-off relay ()0 w ll be in ts energized;positicn, therefore when connector side" switch wiper a7 reaches thethird position, I

gthe' ground GE, which on a connection to an iidleline caused the lineswitch to step, will now find an open point atcontact Glofrelayf 106,and stepping magnet TS .of the called Iline switch M will not .bedisturbed. The

calling subscriber will getthe busy tone as follows :ground "GKf'winding94 of busy induction coil IND, busy tone interrupter BT, through thesource of current to ground at .GJ. Thiscircuit induces a tone into, the

winding .95 of busy induction coil IND which is caused .to flow over thefollowing circuit z ground G'IQwinding 95 of busyin- 'duction coilfIND,wire37 condenser .78,

t ct 5.0, new 169; ine s tc Wipe W .3 t unk 1 i i32, r lay IM .0 @0114contact 79 of relay OC, trunk wire63, termina l62,;connectorwiper M sideswitch wiper Hand third position thereof, impedance coil to ground GE.Because off the high irnpedance of c 'il'X, part .of thls tone currentivillibe. forced'by way of contact 67 of relay cc ta tfi fofrclay .Cfiyi e c n u t I, su

st tion apparatus line conductor R, conhec or 9N, throug th ourc of urto telephone at A, the calling subscriber will hear the busy tone. a

If the called line becomes idle while a connector CN is waiting on itsterminals; the called line switch will immediately advance to the properpoint when connection will be made as preyiousl-y described for a casewhere the called line .was not busy.

more than one connector is waiting on the terminals or" a line when it'becomes idle, the called line switch can only connect with one of them(which will be the one corresponding [to the next nearest point ontheline switch bank) because the called line switch muststep to a differentpoint on 1ts'bank for each connector which calls it and ,the lmeswitchwipers can only rest on oneset of terminals at a time.

After the conversation is completed, the connection is released, by thehang ng up of the call ng subscribers receiver, in the following manner:The .circuit for relay IMP is opened by contact 2' at the hook switch of'substation A which allows relay ills [P to ,deenergizeand open thecircuit for relay RL at contact 17. Relay RL, after short time, releasesand closes a circuit from ground GA, contact 16 of relay IMP, contact 18of relay BL, oil normal'contact -96, winding of release magnet REL .tothe source of current. The magnet REL upon energizing. restores the.connector switch shaft and side switch to normal after which its owncircuit is broken at off normal contact 96. The magnet REL, uponenergizing alsoopensthe circuit leading to the winding '23 of thecalling line switch out off relay CO. This circuit is opened at contact33 or" magnet REL and allows the line switch out off relay GO todeenergize.

y The connector is now'in position to be again selected because there isagroundfiGA, through contact 16 of relay IMP, contact 118 of relay RL,0E normal contact 19 on its test trunk 20.

Both the calling and the called line switches L andM remain where theywere during conversation. until again used.

ilt will of course be understood that the lines having the substations Aand B, may

u ua first s lect r, and i esi e se le t r swi h m hanism between h i Swt es of a g up a dccnnect s tch such as UN, for a plurality of groups,that' t e ystem m y be m d of any size a fu lm y be had c the princip on i hich re in ogu in th art a t .nr sent time y Vi tu 9 wh ch the ad aa s o such-t nking ci cu sin yhe ha a in a clit cn th dva tages of .mysi j enid "9L- .Als th scir iut nc ud t er 431W be added ite a Q, as

In the embodiment illustrated, although the tirst'selector switch isnotdescribed in detail, it is indicated by its switch wipers .connectedto the conductors 29,32, 34 and 20, andwhich are shown in the drawing ase'n aging passive contacts of the connector switch, CH. lt Wllli beunderstood in the art how such engagementwill be controller by thecalling switch mechanism, and no detailed description of such operationas maybe necessary to cause such engagement, will therefore herein behad. a

It will beunderstood, that if desired, the lines having the substationsA and B may have common access by their respective line switches L and Mto the same trunk circui't, such as the trunk circuit UN, for in 1connector switch CN, may be multiply constance, in such a case the lineswitch sets o't contacts consistingct the contacts 28,-

Sl, 35,105 and 15 of the line switch L and which setof contacts areassociated with the nected to the line switchset or contacts 28, 105 and15 of the line switch M. Although I have. illustrated and described aspecific embodiment of my invention for the purpose of imparting a clearunder-% standing of the same, it will be understood that I am aware thatnumerous and extensive departures may be, made from the embodnnentillustrated without departing from the spirit or the invention, but whatI claim as'my invention is defined in the followin claims:

1. n a telephone system, the combinae tion with a plurality of telephonelines. a

p urality of connector switches, calling line apparatus for directivelycontrolling said connector switches means including a non.

'umerical switch to interconnect, a calling one ofthe said lines with anidle one of the said switches, a test wiper for the said con- .nectorswitch, passive contacts, one for each of the lines adapted to beengaged by the said test wiper, controlling apparatus for the saidconnector sw 1tches,a circuit for each of the lines leading to saidcontact for that line on each connector, switch, and means responsive tothe continuity of the said circuit when the said test wiper engages acalled line contact to extend atalking circuit from the calling line tothe called line through the said connector switch.

closure of calling line circuit conductors to operate a calling lineswitch to connect with an idle one of the said selective switchesthrough the calling contact set of the calla ing line switch, meansunder the control of calling line apparatus and connected selec tiveswitch to operate the calledline switch to cause'it to make connectionwith a called set of contacts of the called line switch, and meansincluding wipers of said selective switch for interconnecting the saidcalling line switch calling contacts and said called line switch calledcontacts to extend a talking connection between the calling and calledlines through all of .the'said switch contacts.

3. In a telephone trunking system, the combination with a plurality oftelephone lines, line s vitches for the lines, active switch wipers forthe line switches connected. to circuit conductors individual to thelines, successive sets of passive contacts for each of the lineswitches, some of the said sets being connected to circuit conductorsleadto onetype of trunk circuit, other sets l; ,ing connected to circuitconductors leading to another type of trunk circuit, means responsive toa closure of the line conductors of a calling line to move the activeswitch wipers oi said calling line switch into engagement with a set oicontacts, whose connected circuit conductors lead to a trunk circuit ofthe first type, switching means responsive to the directive control ofthe call-v ing substation apparatus to completea conparatus to cause thesaid called line switch to advance its active switch wipers to makeconnection with the set or contacts connected to the trunk circuit ofthe second type with which thetrunk circuit apparatusof the said trunkcircuit has made connection.

4;. In a telephone system, the combination with a plurality of telephonelines, substa-c tions for the said lines, a line relay for each of thelines in circuit with the line substation, a line switch for each of thelines, active switch contacts and passive switch contacts for the saidline switch, propelling means for propelling the active switch contactsof line switch to cause them to make contact successively with differentsets of passive switch contacts, the said passive contact set-s being intwo groups, one group being incominc: contact sets, the other groupbeing outgoing contact sets, astopping circuit for the said propellingmeans having two branches, one of the said branches being normallyclosed and the other of said branches being normally open, meansresponsive to the continued closure of the closed branch to cause thesaid active switch contacts to'be stopped when they engage the contactsof a par ticular trunk circuit associated with a given contact of one ofthe groups, and means responsive to the closure of the other branch andthe opening of the first branch to cause tactso'f a line switch to causethem to make contact successively with-different sets of passive-switchcontacts, the said passive contact sets being in two groups, one groupbeing incoming' contact sets, the 'other group leeing outgoing contactsets, a "stopping circuit for the said propelling means having t wobranches, one 'of the said branches/being shimmy closed and the other ofsaid branc'he's beingnormally-op'en, m'eans responf'srve 't'o thecontinued closure of the closed branch to cause the said active switchcontacts to be stopped when theyv engage the contacts of a particulartrunk circuit associated witha given contact of one of the groups, andmeans responsive to the closure of the 6therhranch-and the opening ofthe first branch to cause the said active contacts to stop when inengagement with the first engaged set of contacts of the other group,said line relay magnet for an associated line switch controlling theopening of one of the said branch circuits, and the closure of the otherbranch circuit.

6. In a telephone system, the combination with a plurality oftelephones, a line relay for each of the lines, a cut-off relay for eachline relay, a common source of busy tone current, a link circuit adaptedto be connected with a calling line, a contact of the said link circuitadapted to make connection with a contact of a desired called line, anda busy tone circuit arranged to extend a connection between the saidcommon source of busy tone current and the talking conductors of acalling line, including normally open contacts of the calling linecut-oftrelay, said link circuit contact, and said calling line lint:circuit connecting means.

7. In a telephone system, the combination with a plurality of telephonelines, substations for the said lines, line switches for the said lines,said line switches comprising a set of active switch wipers and sets ofpassive switch contacts adapted to be successively engaged by themovement of the said active switch wipers, means to move the said activeswitch wipers, the said passive sets of coin tacts comprising callingand called sets, means responsive to the connection of a sub station toa calling line circuit to cause the said switch wiper moving means tooperate, a plurality of link circuits, incoming terminals and outgoingterminals for the said outgoing terminals of the diii link circuits,theincoming terminals and. the 'ent li-nk circuits hem connectedtodiil'erent. contact sets otthe dinerent line switches, meansresponsive to the electrical condition of an incomine contact of the setof contacts oi a given link circuit to s op the m :ent of a calling lineswitch-when its ctire switch contacts come into enpga neat with the saidcontact set, selective ,g means for the said erthe control of callingSubs to cause the movement of link circuit und station appara the calledline s a itch active contacts, and controlling means associated withthesaid selective switching means to alter the electrical conditioncontact. of a set ot'contracts associated with the called line switchand with the said linlt circuit, which set of contacts is with referenceto the said link circuit an outgoing set of contacts for the said calledline switch, whereby the morement of the said called line switch isstopped when its active switch cont cts engage :the said outgoingcontact set. I

in a telephone system, the combination with a plurality of telephonelines,v sub stations-tor the sai lines, line switches. for the saidlines, said line switches comprisinga set ot QCi-lYQ switch wipers andsets of: passive switch contacts adapted to be successively engaged bythe movement oi the said active switch wipers, means to move the saidactive switchwipers, the said passive sets of contacts comprisingcalling and called sets, means responsive to the connection of asubstation to a calling line circuit, to cause the said si 1 wipermoving means to operate, a plurality of link circuits, incomingterminals and outgoing; terminals "for the said link circuits, theincoming, terminals and the outgoing terminals of the different linkcircuits being connected to different contact sets of the different lineswitches, means responsive to the electrical condition of an incon'iingcontact of the set of contacts of a given link circuit. to stop themovement oi a calling line switch when its active switch contacts comeinto engagement with the said contact set, selective switching; meansfor the said linl: circuit under the control of calling substationapparatus to cause the movement of the called line switch act vecontacts, controlling means associated with the said selective switchingmeans to alter the electrical condition oi a contact of a set orcontacts associated with the called line switch and with the said linkcircuit, which set of contacts is with reference to the said linkcircuit an outgoing; set of contacts for the said called line'switch.whereby the movement of the said called line switch is stopped when itsactive switch contacts engage the said outgoing contact set and acalling circuit extended from the calling; line, through the said linkcircuit, through active contacts oi the calling and called line switchesand passive incoming and outgoing contacts at the calling and calledline switches respectively, for the said link circuit.

9. In a telephone system, the combination with a plurality ofsubscribers telephone lines, line switches for the lines, numericalswitches adapted to be selected by a calling line switch, and meansunder the control of a numerical switch to cause the operation of acalled line switch and a talking circuit established through contacts ofthe line switches of calling and called lines and ot said numericalswitch.

10. In an automatic telephone system, a plurality of telephone lines, asingle indi vidual line switch for each line, a numerical switcharranged for primary and secondary movements, outgoinglines from saidnumerical switch, means for causing the individual line switch of thecalling line to seize said numerical switch, means to operate saidnumerical switch to seize an outgoing line, and means to cause the lineswitch oi the called telephone line to hunt forthe seized outgoing line,said calling and called line switches and said numerical switch bciugretained in the established connection.

11. In a telephone system, the combination with a plurality ofsubscribers telephone lines, line switches normally remaining in theposition last used, and a nun'ierical switch adapted to be selected by acalling line switch, of means under the control of a numerical switch tocause the operation of a called line switch, and a talking circuitextending through the line switches of calling and called lines and saidnumerical switch.

12. ln a telephone system, the combination with a plurality ofsubscribers telephone lines, line switches for the lines, individualoperating means for each 01 said line switches, and numerical switchesadapted to be selected by calling line switch, of means under thecontrol of a numerical switch to cause the operation of the line switchof the called line, and a talkingcircuit established through contacts ofthe line switches of calling and called lines and of said numericalswitch.

In witness whereof, I hereunto subscribe my name this 9th day of Jan, A.D. 1919. VVINFRED T. .PONELL.

